Molded wood or paper pulp food trays have served the food packaging industry well for many years for the packaging of fresh meat, fish and poultry. Such trays have the advantage, besides low price and low cost to the consumer, of being clean, sturdy and safe; of being biodegradable so as to minimize the solids pollution problem; of being capable of assimilating the free liquid juices which exude from fresh meat, fish and poultry; of being air and vapor permeable so as to maintain color and freshness of meat and permit passage of liquid vapors. Nevertheless, in spite of the many advantages of such molded wood pulp trays, certain locales have effectively outlawed their usage by the requirement that a very high percentage of the food packaged therein be visible to the consumer and since wood pulp is normally opaque, such trays have not met this legal requirement.
Consequently, in such locales the only packaging trays utilizable in view of such laws are clear plastic trays. These clear plastic trays have many defects, some shared with foam plastic trays, including reduced strength, increased usage cost because of lack of important functional features like blood control that results in higher rewraps and/or downgrading of meat; such trays have sharp edges which tend to cut the packaging film and/or hands. These trays collect liquid exudants in puddles from the fresh meat, fish and poultry packaged therein, thereby not only causing discoloration of the packaged product, but also serving as a bacterial breeding ground and further serving to opacify the package itself and provide distortion in the remaining transparent areas thereby contributing to the very problem which such trays were designed to overcome; blood that goes under the tray acts to release the sealed film causing soiled hands, soiled check-out counters, leaking packages, etc. In addition, the conventional plastic trays, being formed of non-breathable material, inhibit oxygen migration to the meat at the bottom of the tray; this causes further discoloration of the meat and it is well known that fresh red meat in plastic trays deteriorates on the bottom first.
Another defect of the clear plastic trays involves their transmission of light along the plane of the tray walls, i.e., a light pipe or fiber optic effect; this causes further discoloration of the bottom of the meat. Light transmitted through clear plastic trays has a negative effect on fresh meat quality as it causes relatively rapid discoloration when compared with the effect of natural or artificial light on meat packaged in otherwise similar conditions. Because of the light pipe effect, meat packaged in clear plastic has its bottom exposed to light constantly even when the tray rests on an opaque object such as the bottom of the meat cooler or an underlying package or between two packages.